#define   _CRT_SECURE_NO_WARNINGS 1
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
int maxDepth(struct TreeNode* root) {
    if (root == NULL)
        return 0;
    int LeftHight = maxDepth(root->left);
    int RightHight = maxDepth(root->right);
    return LeftHight > RightHight ? LeftHight + 1 : RightHight + 1;
}